Fueling nozzles for the underwing fueling of aircraft have been known since wings having a hollow interior space capable of containing fuel for the aircraft's engine were first utilized. To fill such a tank with fuel requires the transfer of liquid fuel (which often may comprise a kerosene distillate fraction) from a reservoir in which it is contained to the aircraft's fuel tank. Such transfer typically involves the use of a conduit that typically comprises a flexible hose, one end of which is connected to the outlet of a fuel pump and the other end of which is connected to a fueling nozzle portion. The nozzle portion is typically of an investment cast construction, and comprises one half of a quick-connecting/disconnecting mating couple, the other half of which (the nozzle-receiving portion) is an integral part of the outlet portion an aircraft's fuel tank and is disposed at the opening of the fuel tank at which fuel is admitted during a re-fueling operation. Under such an arrangement, the nozzle may be quickly connected to the fuel tank, and fuel may be pumped from the reservoir through the conduit and nozzle, and into the tank. The mating couple which comprises the nozzle portion as one half is generally fitted with sufficient sealing provisions to preclude the leakage of fuel from the transfer system (reservoir, conduit, pump, nozzle, and nozzle-receiving portion of an aircraft fuel tank) to the surroundings during the re-fueling operation.
Although it is possible for a fuel tank that is contained within an aircraft wing to be filled with fuel from a sealable opening located at the top of the wing, bottom of the wing, or even on the side of the wing, practical field operations have shown that it is fastest, easiest, and thus most practical for ground crews to re-fill the inner wing fuel tanks of commercial aircraft using a sealable opening that is located on the bottom or underside of the wings of the aircraft. Towards this end, various nozzles and nozzle configurations have been developed over the years to simplify the re-fueling operation, to minimize time associated with the re-fueling operation, and to maximize the safety level of the overall operation from the standpoint of all persons involved, including passengers, the air crew, and the ground crew.
One requirement of the re-fueling operation is that the nozzle comprise a means by which it may be rapidly connected and disconnected from the nozzle-receiving portion of an aircraft tank. This requirement is accomplished by constructing the nozzle that is to be attached to the fuel tank from an inner conduit portion that is substantially circular in cross section, and an outer sleeve portion. The inner conduit portion is essentially a straight pipe having attached at one end the fuel delivery hose, and having at its other end a flange which mates with the nozzle-receiving portion of the aircraft's fuel tank. The outer sleeve portion is coextensively disposed about the inner conduit portion, and the outer sleeve portion terminates at approximately the point where the inner conduit portion terminates at the fuel delivery end of the conduit, and at this end the outer sleeve portion comprises a means for securing the fueling nozzle that comprises such conduit/sleeve assembly in rigid position when placed in the nozzle-receiving flange on the aircraft.
One desirable means for securing the fueling nozzle to the nozzle-receiving flange of an aircraft's fuel tank is a means which permits a refueling technician to place the end of the nozzle from which fuel is delivered into the nozzle-receiving flange on the aircraft, and twist or turn the outer sleeve portion of the nozzle assembly in a mono-directional single motion so that a sealed mating of the fuel tank opening and the fuel delivery end of the nozzle conduit is formed by virtue of such twist or turn, and the outer sleeve portion is thus effectively locked in place. Such fueling nozzle assemblies are known in the prior art, and include those described in U.S. Pat. Nos. 2,665,926; 2,753,884; 3,168,125; 3,441,055; 4,328,844; 4,567,924; 4,638,842; 4,794,960; 5,405,120; 5,540,413; 5,765,601; and 5,904,302, the entire contents of each of which are herein incorporated by reference. While one preferred means for locking the outer sleeve portion in secure position on the nozzle receiving flange is described in U.S. Pat. No. 5,765,601 any functionally equivalent means known to those skilled in the art for locking the outer sleeve portion in secure position with respect to the nozzle receiving flange portion of the aircraft's fuel tank while simultaneously providing a sealed fit between the aircraft's fuel tank inlet and the fuel delivery end portion of the inner conduit of the nozzle assembly is referred to herein as a means for securing the fuel nozzle to the aircraft.
In accordance with known refueling practice, the reservoir that contains fuel for aircraft is often conveniently located on a motorized vehicle, such as a truck. Conveniently, such truck also typically houses the refueling conduit, such as an approved grade of rubber hose, and a means for coiling the hose when it is not in use. Further, such truck or vehicle also contains a means for securing the fueling nozzle that is attached to the end of the hose. There is also a fuel pump that is fed from the reservoir, which serves to pressurize the fuel to propel it through the conduit hose and to deliver it to the fuel tank. The fuel pump contains a pressure-regulating means which may be adjusted by the re-fueling technician to a desires specific level of pressure. It is common practice in the art to set the pressure on a fairly infrequent basis, and then re-test the fuel pressure at intervals to assure its sufficiency. However, this common approach has the serious drawback that in the event that that fuel pressure is inadvertently increased, a refueling technician who refuels aircraft may not be aware of an increased level of fuel pressure at the regulator for quite some time, since conventional re-fueling nozzles are not equipped with pressure gauges on the nozzle itself. Therefore, a person refueling the aircraft has no way of knowing the exact fuel pressure in the nozzle during the refueling operation. This may have serious consequences in cases where the pressure of the fuel being delivered exceeds the maximum pressure rating of the in-wing fuel tanks aboard the aircraft, for it is entirely within the realm of possibility that the fuel tank integrity may be compromised to the point of actual tank rupture, cases of such which have been documented. In such event, the aircraft wing must be dismantled and the fuel tank repaired or replaced, and then the aircraft must then be re-inspected for airworthiness, the whole operation of which being very costly and time consuming. Therefore, if a means for monitoring the pressure of the fuel at the point of its entry into an aircraft's fuel tank during the re-fueling operation were readily available, such means for monitoring the pressure would be of great advantage to the owner's of aircraft fleets worldwide, for it would greatly reduce, if not totally eliminate, the possibility of overpressure damage to an aircraft's in-wing fuel tanks as a result of a re-fueling operation. Further, if such a means were devised which was capable of withstanding the physical abuse (impact damage from being dropped) routinely encountered by fueling nozzles, such means would be of long-term benefit. If such a means were provided at a cost which is relatively low, such would be readily welcomed by the aviation industry. The present invention provides a means which satisfies these criteria.